The present invention relates generally to aircraft engines, and, more specifically, to thrust reversers therefor.
Turbofan gas turbine engines are commonly used for powering aircraft in flight. In a turbofan engine, air is pressurized in a compressor and mixed with fuel and ignited in a combustor for generating hot combustion gases which flow downstream through turbines which extract energy therefrom. A high pressure turbine powers the compressor, and a low pressure turbine powers the fan disposed upstream of the compressor.
Propulsion thrust is provided by the combination of the hot combustion gas exhaust from the core engine with the pressurized fan air which bypasses the core engine. In a long duct turbofan engine, the fan air bypasses the core engine inside a surrounding nacelle and is mixed with the core exhaust prior to discharge from the engine in a combined exhaust stream.
During aircraft landing, it is common to employ thrust reversers with the engine in which doors are selectively opened for blocking the aft direction of the engine exhaust and redirecting it in the forward direction for providing additional braking for the aircraft. There are two basic types of thrust reversers having doors mounted either post-exit to the discharge exhaust nozzle, or preexit from that outlet nozzle.
Since thrust reversers are used solely during aircraft landing they must be integrated into the engine with minimal adverse effect during all remaining conditions of operation including takeoff, cruise, and descent. However, in view of the attendant complexity in providing thrust reversers at the discharge end of the engine, the prior art is quite crowded with myriad forms of thrust reversers attempting to minimize adverse affects thereof while maximizing aerodynamic performance of the engine.
Since an aircraft engine is specifically configured for powering an aircraft in flight, engine weight is a primary design factor, and the introduction of a thrust reverser should minimize the corresponding increase in engine weight. Propulsion efficiency of the engine is yet another significant design factor, which is also adversely affected by the introduction of thrust reversers in various forms.
For example, a post-exit thrust reverser includes a pair of clamshell doors which are deployed in the form of an open clamshell for redirecting the engine exhaust in the forward direction during landing. Since the deployed clamshell doors must closely adjoin each other at their trailing edges, when the doors are retracted or stowed, the trailing edges thereof typically form a fishmouth configuration which introduces undesirable aerodynamic drag during normal operation of the engine. Drag is a performance penalty which reduces overall efficiency of the engine with this type of thrust reverser.
In pre-exit type thrust reversers, the reverser doors are located upstream from the discharge end of the nozzle resulting in a typically more complex configuration for integrating the doors in the stowed and deployed positions thereof. In particular, the stowed doors must minimize aerodynamic losses of the exhaust channelled therethrough during normal operation, as well as providing a streamlined outer surface for reducing drag thereover. And, the doors should be suitably sealed to the exhaust nozzle when stowed for reducing or minimizing exhaust gas leakage through the convoluted perimeter of the doors.
Since the exhaust nozzle is annular in configuration, each of the two doors must be suitably arcuate to match the annular configuration of the nozzle when stowed. The two doors are thusly arcuate at their forward and aft ends with relatively straight side edges therebetween, and with inner and outer surfaces which must suitably blend with corresponding inner and outer surfaces of the exhaust duct in which they are mounted.
Adding to the complexity of thrust reverser design is the inherent necessity for suitable actuation thereof for deploying open the doors when required and retracting closed the doors to their stowed positions when not required for aircraft landing. Various forms of actuators are found in the prior art having different advantages and disadvantages, which also increase the complexity of effective sealing of the doors.
Yet another significant design factor for thrust reversers is the integration with the actuating means of suitable safety devices for preventing unintended deployment of the thrust reversers except for aircraft landing. Such deployment prevention must be integrated with the actuating means without introducing excessive weight penalty, yet providing a durable and rugged thrust reverser actuation system for long life thereof.
Accordingly, it is desired to provide an improved thrust reverser with integrated components for enhancing aerodynamic performance in a compact and rugged assembly.
A thrust reverser includes a pair of doors covering corresponding portals in an exhaust duct between an inlet and outlet nozzle at opposite ends thereof. The duct also includes a pair of side beams having actuators mounted thereon, and operatively joined to the doors for selective rotation thereof about corresponding pivots. Blister fairings are disposed inside the duct and sealingly join the doors to the beams around respective ones of the pivots.